Telegraph.



No. 693,605. Patented Feb. lax-.1902.

- F. E. Dl-IUMY.

TELEGRAPH.

(Applibation mm Octl 14; 1901. (No lflo dal.) a sheets-sheet l.

- No. 693,605. Patented Feb.. l8, I902.

F. E'. DHUMY.

. TEIZEGBA PH.

g ueafiion filed me. 14, 1901.

3 Sheets-Shoot 2.

(No Model.)

THE NoRms PETERS 00.. PNOTD-LIYNO., WASHINGTON bunt No. 693,605. Patented Feh.'l8, I902.

F. E. DHUMY.

TELEGRAPH.

v (Application filed Oct. 14, 1901. ([40 Model.) 3 Sheets8haet- 3.

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\ UNITED STATES ATENT FFICE.

FEBNAND E. DIHUMY, OF BOSTON, MASSACHUSETTS.

TELEGRAPH.

S PECIFICATION forming part of Letters Patent No. 693,605, dated February 18, 1902. Application filed October 14, 1901. Serial No- 78,525. (No model.)

To ctZZ whom iv may concern.-

Be it known that I, FERNAND E. DHUMY, of Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Telegraphs, of which thefollowing is a specification.

This invention relates to multiplex. telegraph systems in which reversals of polarity are used either alone or with other expedients for the purpose of transmitting signals simultaneouslyin opposite directions over the same wire. It is applicable to all classes of the above type, including the various forms of the ordinary duplex and quadruplex telegraphs, and to duplex and quadruplex printing devices, such as the Wheatstone automatic. I

It is a fact Well known in practice that the negative pole of the battery orother source of current in polar duplex and quadruplex systems tends to short-circuit through the atmosphere and other media, such as cable insulation and tree -branches, to the earth along the line with greater freedom than the positive polethat is to say, the fall of potential over a given wire will be greater when the negative pole of the battery is to line than when the positi've'pole is to line. In bad weather this effect is increased, and it is directly due to this that quadruplexes often sufier so severely in bad weather as to necessitate abandoning the common 'side ontirely and working only on the polar side. This difference in behavior of the positive and negative currents affects the quadrupleX in two ways. First, the polar reversals at the home station do not reach the distant station evenly owing to the greater drop of potential on the negative side, and there is thus created an intermediate margin in current tension in the common or neutral relay-that is to say, in addition to the increased and decreased current strength intended to operate the neutral relay there is on each polar reversal (intended to operate the polarized relay) a drop and rise inpotential from and to the maximum potential intended to close said neutral relay. The resulting unevennesss in the working margin increases as the insulation of the line falls until it becomes so marked as to seriously interfere With-the signals and necessitate the temporary abandonment of the common side. The second effect is due to the fact that an artificial-line balance taken on the positive pole will not be a true balance on the negative pole, and vice versa, because the negative current escapes to earth more freely than the positive along the main line, while on the artificial-line currents of both polarity pass through alike. Since, therefore, owing to an unequal balance for either or both poles the current will divide unequally between the main line and the artificial line, the outgoing signals will not be wholly n'eutralized on the home relay, and if the insulation of the line is sufficiently low the outgoing signals will become so marked as to seriously interfere with the incoming signals.- This effect is felt on both the polarized and neutral relays, though principally on the latter.

To overcome the above difficulties, I automatically change the balance of the artificial line to suit the different conditions set up by the respective poles, and by so doing I am enabled to maintain a perfect balance with either pole to line, thus properly neutraliz-' ing the outgoing signals,as intended,and making it possible to increase the voltage of the negative pole or decrease that of the positive, so that both poles may reach the distant station at an even voltage. To secure an automatic balance, I employ the improved automatic artificial-line-balancing device hereinafterdescribed and claimed. For the purpose of' equalizing the voltages reaching the distant station I may either increase the voltage of the negative pole or decrease that of the positive. The former method may be carried out by placing an adjustable auxiliary battery or booster between the main-battery lead of negative polarity and thesending instrument or instruments, as hereinafter explained. The latter alternative plan may be carried out by inserting an adjustable resistance between the positive-battery lead and the sending instrument, and this plan I prefer, inasmuch as it is more readily applied to existing apparatus.

My invention consists partly, as hereinafter described and claimed, in an adjustable resistance device of this character having provisions for keeping the resistance-path between the line and the ground through the battery constant on all adjustments for the benefit of the incoming current impulses.

Of the accompanying drawings, Figure 1 represents a diagrammatic view illustrating my automatic artificial-line balancer as applied to a polar duplex-battery system. Fig. 2 represents the balancer and the adjustable resistance device applied to a well-known form of dynamo-quadruplex. Fig. 3 represents a view showing these features of invention applied to another form of dynamo-quadruplex. Fig. 4 represents the artificial-line balancer applied to the VVheatstone automatic system. Fig. 5 represents a booster applied to the negative-dynamo lead in place of the adjustable resistance in the positive lead. Fig.6 represents a modification of the resistance device shown in Fig. 2.

In Figs. 1 to 41 have distinguished the portions of the system which constitute my invention by heavy lines and the old part by lighter lines.

The same reference characters indicate the same parts in all the figures.

Referring to Fig. 1, showing a polar duplex system, 1 is the battery, 2 the pole- .changer, 3 4 the main and artificial lines, 5

the difierentially-wound polarized receivingrelay, and 6 7 the condenser and resistance in the artificial line, all connected and operated in the usual mannerthat is to say, the pole-changer 2 when it is closed places one pole (the positive in this instance) of the battery 1 to line and when it is opened places the opposite pole to line, thus operating the polarized receiving-relay at the distant station, the relay 5 being unresponsive to the outgoing signals because of the current dividing equally between the main and artificial lines through'its ditferential windings. Any other method, such as the bridge method, of balancing the receiving instrument to outgoing signals may of course be followed.

Theoretically the resistance of the artificial line 4 may be made equal to that of the main line 3 by adjusting the resistance 7 in the artificial line; but in practice it is generally impossible to obtain a balance which shall be perfect for both poles of the battery because of the fact that the negative pole escapes to earth along the main line more readily than the positive pole. Thus virtually the resistance of the main line is less for the negative pole than it is for the positive pole, and to equally divide the current between the main and artificial lines resistance should be taken outof the artificial line each time that the negative pole is put to line and restored each time that the positive pole is to line. This result I automatically accomplish, as follows: 8 is an added resistance (made adjustable in practice) in series with the resistance 7 of the artificial line and having its ends connected by wires 9 10 with the back contact 11 and armature-lever 12 of a pony relay 13. The magnet 1.4 of the latter is connected in the 'ficial-line balancer applied.

key-circuit 15, which operates the polechanger 2, so that the relay 13 is operated in synchronism with the pole-changer 2 by manipulation of the-key 16. Then the polechanger 2 is closed, putting the positive pole of the battery to line, the armature-lever 12 of the relay 13 is drawn against its front stop, breaking the circuit through wires 9 10 and placing the resistance 8 in series with the resistance 7. When the pole-changer is open, placing the negative pole of the battery to line, the armature-lever 12 will reside against its back stop 11 and the resistance 8 will be bridged or cut out by the completion of the circuit through wires 9 10.

A balance is taken by first leaving the polechanger 2 open, thereby placing the negative pole "to line and adjusting the resistance 7 to that of the main line. After that the positive pole is placed to line by closing the polechanger, and the added resistance 8 is adjusted until it and the resistance 7 equal that of the main line.

Referring now to Fig. 2, which shows an embodiment of my invention as applied to a well-known form of dynamo quadruplex-key system, 20 21 22 23 represent the four dynamo-machines designed to give stronger and weaker positive and negative currents, the leads of the machines being connected, respectively, with the ground via wire 24 and with the front and back contacts of the pole changers 25 25 in the usual manner. 26 is the transmitter, 3 and 4 the main and artificial lines, and 5 and 27 the polarized and neutral relays, all arranged as usual. 8 is the added resistance in the artificial line, alternately cut in and cut out by the action of the relay 13 on changes of polarity, as hereinbefore described, the magnet 14 of relay 13 being located in the key-circuit of the polechangers 25. In this arrangement I take a balance with long ends to line-that is, with transmitter 26 closed. I first leave the key 16 open, which puts the negative machine 22 to line and cuts out the resistance 8 in the artificial line. The resistance 7 is then adjusted to equal that of the main line, after which with the key 16 closed and the positive machine to line and the resistance 8 in series with resistance 7 the resistance Sis adjusted until it and resistance 7 equal the resistance of the main line.

Fig. 3 illustrates the application of my invention to another well-known form of quadruplex in which only two dynamos 20 and 22 and a single pole-changer are employed. In this arrangement I have shown the magnet 14 of relay 13 as located in the key-circuit 15 of the pole-changer, as before.

Fig. 4 shows a portion of the well-known Wheatstone automatic system with my arti- 28 is the oscillating disk of the pole-changer, on the periphery of which disk I locate a projection 29, adapted to engage and release a lever 30, normally held by a spring 31 against a con- IIO tact 32. The lever and contact constitute a switch included in the circuit 9 10 of the added resistance .8 in the artificial line,which switch is closed when the disk 28 oscillates, as shown in the drawings, to ,place the negative pole of the battery to line and opens when the positive pole is placed to line. I

The foregoing are typical systems selected to illustrate the operation of. my artificialline balancer; butit will be understood that the device is susceptible ofembodiment in various other ways as well.

As the negative voltage reaching the distant station is cut down more than the positive by the more rapid escape to earth of the negative current along the-line, it is desirable in conjunction'with my automatic artificialline balancer to increase the negative voltage or decrease thepositive. The former method is illustrated in Fig. 5, in which 33 represents an auxiliary battery or booster comprising several cells and tapped at intervals by wires leading to a series of contacts 34 34, the first one of which is connected to the lead of the negative dynamo 22. A pivoted arm 35, adapted to make contact with any of the points 34, connects by a wire 36 with the pole-changer, whereby t'he'negative current may be adjustably inoreasd, for, however, instead of increasing the negative voltage to reduce the voltage of the positive pole, and to this end have devised the novel resistance device shown in Figs. 2 and 3, (with a modification in Fig. 6,) whereby the resistance-path presented to the outgoing signals over the line may be adjusted withcontact of the pole-changer.

out varying the resistance for the-incoming signals.

In place of the usual resistance in the lead from the positive machine 20 to "the pole-- changer, corresponding to the resistances shown in Fig. 2, as placed in the leads from the machines 21 22 23 to the pole-changers, I locate the resistance device 50, comprising a resistanceconductor 51, connected at one end with the lead or Wire 52 from the dynamoand grounded at the other end through wire.

53, and a second resistance-conductor 54, having a blind termination at the end corre sponding to the dynamo end of the resistance 51 and connected at the other end by the sending and receiving wire 55 with the front The resistanceconductors 51 54 each consists of a series of resistance coils or sections 56. 57, located be: tween tap-points or contacts 58 59. Y

is a pivoted arm adapted to electrically connect the tap-points 58 59 of the respective resistance-conductors in pairs, or, in other words, to tap the conductor 54 onto the conductor 51 from different points on the former to different points on the latter.

Let it be assumed, for illustration, that the coils 56 are each of one hundred ohms resistance, as indicated in Fig. 2, and the coils 57 are each of a smaller resistance. It is evident that as the arm 60 moves out from left,

1 pre-' to right it adds resistance in the line-wire 52 55, reckoning outwardly, for at each successive step to the right it adds to the line a resistance-coil 56 of one hundred ohms and cuts out a coil 57 of less resistance. The voltage sent out overthe line by the positive machine 20 is therefore successively reduced by moving the arm 60 to the right and increased by moving it in the opposite direction. 61 is a fixed resistance-of two thousand four hundred ohms located in the Wire 53 between the last tap-point 58 and the ground. It will be noted that all ofthe resistance-conductor 51 to the left of the arm 60 and all of the conductor 54 to the right of said arm are parts of the line, while all of the conductor. 51 to the right of the arm 60 constitutes a leak branching to ground from the line. Now reckoning back fromthe pole-changer it will be seen that an incoming current has first to traverse such portion, if. any, of the resistance54 as is on the right-hand side of the arm 60 until it reaches said arm, after which it has two paths to the earth, one directly by wayof the resistance 61 and such portion of the resistance 51 as may be on the right of the arm 60 and the other by way of such portion of resistance 51 as may be on the leftof said arm and the dynamo 20. These two paths have a certain joint resistance which increases as the arm 60 moves from left to right. The resistances of the coils 57 in the conductor 54 are so calculated that this joint resistance added to the resistance in the conductor 54 to the right of the arm 60 is always substantially a constant quantity, and thereforethe incoming signals are not disturbed by changes in the outgoing positive voltage due to shifting the arm 60, The ohmic resistances of the different coils 57, calculated on the basis of the quantities given for the other resistances andfor the number of coilsshown, are given on Fig. 2.

In the arrangement shown in Fig. 3'the re* sistance device50 is inserted between the positive machine 20 and the pole-changer 25 in a manner similar to its arrangement in Fig. 2.

Fig. 6 illustrates a modification in the means for bringing successive tap-points together in the two resistance-conductors of the device 50. The conductor 54 is mounted on the pivotedarm 60 with its contacts or tap-points exposed in position to make direct contact with those of the conductor 51 and the latter is mounted in curved form with its tap-points 58 in different angular positions and at radial distances equal to the radial distances of the tap-points 59.

I claim- 1. In a telegraph system, a main line, an artificial line, a polarized receiver, pole-chan ging means, and current-supplying means, ar-

ranged substantially as described, and means 4 having provisions. automatically to increase the resistance of the artificial line when a positive pole is placed to line and to decrease said resistance when a negative pole is placed to line.

2. In a telegraph system, a main line, an artificial line, a polarized receiver, and polechanging means, arranged substantially as described, an added resistance in the artificial line, and a switch connected to open and close synchronously with the periods of the polechanging means and arranged to cut in and cut out said added resistance.

3. In combination, a resistance-conductor, a second resistance-conductor, and a movable device having a series of predetermined positions in whichit connects a series of points of the first resistance-conductor with a series of points of the second resistance-conductor, the arrangement being such that the joint resistance of the two portions of the first resistance-conductor on opposite sides of the tappoint added to the resistance of the second resistance-conductor on one side of the tappoint is substantially a constant quantity in all of said positions of the movable device.

4. In a duplex telegraph system, a sending and receiving wire having a sectional resistance divided by a series of tap-points, a grounded wire having a sectional resistance similarly divided, means to send current impulses through said grounded wire,and a movable device having provisions for tapping the sending and receiving wire from different points in its resistance onto the grounded wire at different points of the latters resistance.

5. In a telegraph system, a main line, an artificial line, and a polarized receiver, arranged substantially as described, independent sources of positive and negative current, pole-changing means to connect said sources alternately with the line, and a resistance device interposed between the positive source and the pole-changing means and so arranged as to act permanently to reduce the line-voltage from the positive source below the linevoltage from the negative source, said device including a sending connection between the positive source and the pole-changing means, and a leak branching to ground from said connection.

In testimony whereof I have affixed my signature in presence of two witnesses.

FERNAND E. DHUMY. Witnesses:

A. D. HARRISON, R. M. PIERSON. 

